Hearing Conservation – the Facts Behind the Figures

Legal exposure limits to noise vary depending on the length of exposure, but since compliance with this exposure limit should be checked for every employee, it is necessary to ascertain the sound attenuation for each individual.

However, suitable hearing protection devices are usually selected based on their performance in optimum conditions.

In a recent study by the German BGIA (now IFA - Institute for Occupational Safety and Health of the German Social Accident Insurance), the findings of which were published in Health & Safety International, the reasons for reduced sound attenuation in the field - for custom made hearing protection - included the ear canal widening after extended use; products exhibiting leakage - especially those not tested for leakage; and lack of marking and short stubs leading to left and right devices being reversed.

The results of a field study also indicated that real-world attenuation is lower than the laboratory values for all types of hearing protectors, with formable ear-plugs and the combination of ear-muffs and ear-plugs the highest at 9dB, and custom-moulded ear plugs subject to regular functional checks the lowest at 3dB. It is worth mentioning that custom-moulded ear plugs not subject to regular functional checks displayed a 6dB differentiation - more than the 5dB exhibited by pre-formed ear-plugs, ear-muffs and headband earplugs.

It is clear, therefore, that while custom-made hearing protection devices can offer the best protection against noise-induced hearing loss, their optimum performance depends on the correct fitting and regular functional checks.

In South Africa in the mining industry, MHSA (Mine Health and Safety Act) regulations stipulate that the noise exposure limit is no more than 85dB. It also mandates that after December 2008, the hearing conservation programme implemented by the industry must ensure that there is no deterioration in hearing greater than 10% amongst occupationally exposed individuals. In addition, by December 2013, the total noise emitted by all equipment installed in any workplace must not exceed a sound pressure level of 110dB(A) at any location in that workplace, including individual pieces of equipment.

Our Noise-Ban Elite custom-made hearing protection devices offer optimum protection for those operating in noisy environments, while still providing the opportunity for communication.

These custom made hearing protection devices are part of the H.A.S.S. Hearing Protection Programme that includes custom impressions, computer-aided fitting (including a leak-tight test), and training, monitoring and on-site service by SABS-accredited H.A.S.S. staff.

These devices are backed by ISO 9001/2000 accreditation, the SABS-approved Performance Mark, as well as annual monitoring and ongoing end-user training.